A. Field of the Invention
The present invention relates to cleaning and degreasing apparatus, and in particular to a system, driven solely by compressed air or other inert gas, for cleaning, rinsing, and drying soiled articles.
B. Description of the Related Art
A wide variety of manufactured items acquire layers of grease or other contaminants during fabrication, storage or use. Such items include printed circuit boards, electronic components, machined metal parts and assemblies, and components fabricated from plastic, glass and ceramic materials. In order to maintain the usefulness of these items, they must be periodically (or at least initially) rendered free of contaminants.
Conventional degreaser designs provide for subjection of the soiled article to the action of one or more solvents, followed by removal of residual solvent by drying. For reasons of economy most systems avoid the use of water, which must typically be provided in deionized form and disposed of in an environmentally responsible fashion. In older commercial systems, a single organic solvent having a high vapor pressure could be employed to clean, rinse and dry a soiled article; the solvent's volatility ensured rapid and complete solvent removal. However, recent statutory and regulatory environmental restrictions have severely limited the availability of high-vapor-pressure cleaning liquids that exhibit adequate solvency power.
Therefore, current degreasing techniques typically involve sequential application of multiple solvents. For example, a low-vapor-pressure, high-boiling-point solvent may be employed to clean soiled articles, which are then immersed in a high-vapor-pressure "rinsing" solvent; the latter component, while deficient in solvency strength, readily removes the cleaning solvent and is itself easily evaporated. Multiple-solvent arrangements permit each solvent in the sequence to be utilized to maximum advantage.
Degreasing devices, particularly those adapted for multiple solvents, are often rather complex. Even units that omit means for heating the solvents typically require the interaction of agitation components, drying assemblies, and drainage and exhaust systems for effective operation. Such devices ordinarily depend on electric power.
Unfortunately, electrical components can present unacceptable safety hazards in an environment that often favors use of solvents that may be combustible or flammable. Absent elaborate (and expensive) isolation designs, electrically powered degreasers generally cannot be used with such solvents. Moreover, the danger of combustion is increased by the need for conventional degreasers to remain open to the atmosphere, permitting the entry of oxygen into the solvent-vapor zone and thereby increasing the susceptibility of the vapor to ignition.